Dr. Steven Danyluk/Stephen Zagarola POLARITEK TECHNOLOGY FOR QUANTITATIVE STRESS EVALUATION OF PET CONTAINERS Dr. Steven Danyluk/Stephen Zagarola Atlanta - June 25-26, 2018 PETnology AMERICAS 2018

1978 THE BIRTH OF A NEMESIS

INTRODUCTION TO POLARITEK POLARITEK STRESS MEASUREMENT OUTLINE INTRODUCTION TO POLARITEK POLARITEK STRESS MEASUREMENT THREE CASE STUDIES CONCLUSIONS

POLARITEK SYSTEMS, INC. Founded in 2012 by Dr. Steven Danyluk Patented technology for quantitative full field stress measurement for the polymer, photovoltaics, and aerospace industries Based on > 20 years of development at the Georgia Institute of Technology POLARITEK SYSTEMS, INC.

POLARITEK STRESS MEASUREMENT

STRESS FUNDAMENTALS Stresses in solids - externally imposed or internal (fabrication & processing) Internal (residual) stresses - not subject to mechanical equilibrium ( 𝐹≠0 , 𝑀≠0 ) Forces causing residual stresses - balanced on a microscale: grain boundaries, dislocations and molecular stretching Fracture – results when residual stresses superimposed on external stresses exceed strength of material. Patented Polaritek technology - photoelastic stress measurement method

STRESS FUNDAMENTALS Measurements w/light of various wavelengths using digital photoelastic methods. Measurements can be of stress, strain, displacement or other material properties. Applications in this presentation are residual stresses in PET.

LIGHT TRANSMISSION IN BIREFRINGENT MATERIALS Local (privileged) direction due to stress Polarizer Light source, P and QWP A, QWP and camera Transmitted intensity depends on the wavelength and retardation Light source (white) Many wavelengths polarized due to polarizer *Local Intensity will depend on retardation and wavelength, polarizer/analyzer orientation, and the orientation of the stress relative to the polarizer *Image appears colored since -- particular wavelengths slow up on traversing the thickness and the local stress magnitude and orientation

PHYSICS OF LIGHT TRANSMISSION IN BIREFRINGENT MATERIALS Stress (Plane Stress condition in PET Stretching) Transmitted intensity due to in-plane stretching Optic axis PET becomes biaxial when stress is applied or formed during stretching. In normal incidence light travels along the optic axis, and the orientation and magnitude of the stress are determined from the local color and fringe density.

POLARITEK STRESS MEASUREMENT Light source, P and QWP A, QWP and camera Bottle Measurement Geometry

POLARITEK STRESS MEASUREMENT Stress algorithm produces Fringe and Stress Maps Stress Map 1 2 Data Acquisition (automated) Ten images by rotating optic elements 10 Fringe Map

POLARITEK STRESS MEASUREMENT Whole-field maximum shear stress distribution of bottle/preform base, preform body Determining the mode of stretching Radial Stretching (Uniaxial) Biaxial Stretching Micro Cracks Location of Biaxial Points relative to the gate center Symmetry of Stretching StressMap Stress Map

POLARITEK STRESS MEASUREMENT StressMap Whole-field maximum shear stress distribution of bottle/preform base, preform body Determining the mode of stretching Radial Stretching (Uniaxial) Biaxial Stretching Micro Cracks Location of Biaxial Points relative to the gate center Symmetry of Stretching Fringe map

POLARITEK STRESS MEASUREMENT StressMap Primary Biaxial Point Biaxial Point near GATE Secondary Biaxial Point Whole-field maximum shear stress distribution of bottle/preform base, preform body Determining the mode of stretching Radial Stretching (Uniaxial) Biaxial Stretching Micro Cracks Location of Biaxial Points relative to the gate center Symmetry of Stretching

STRESS MEASUREMENT IN PET CONTAINER BASES THREE CASE STUDIES

PET STRESS MEASUREMENT KEY MEASUREMENT AREAS

PET STRESS MEASUREMENT 3 4 5 1 2 KEY MEASUREMENT AREAS

PET STRESS MEASUREMENT 3 4 5 1 2 KEY MEASUREMENT AREAS

PET STRESS MEASUREMENT Biaxial Stress Pt. Max Stress STRESS MAGNITUDE ISOCHROMATIC FRINGES Isochromatic fringes in Measured Area

PET STRESS MEASUREMENT Distance Biaxial Stress STRETCHING Gate ISOCHROMATIC FRINGES Isochromatic fringes in Measured Area

PET STRESS MEASUREMENT Irregular Stress Field Spherulite Defect VISUAL QUALITY ISOCHROMATIC FRINGES

PET STRESS MEASUREMENT SYMMETRY Greater differences in Fringe Counts = More Asymmetric DIFFERENCE IN FRINGE COUNT ALONG RADIAL AXIS

CORRELATION OF STRESS CRACK RESISTANCE WITH STRESS MEASUREMENTS CASE STUDY 1 CASE STUDY 1 CORRELATION OF STRESS CRACK RESISTANCE WITH STRESS MEASUREMENTS

Biaxial Pt. Distance = 7.6 mm CASE STUDY 1 MAX SCR = *91 min Stress = 16.0 MPa, Biaxial Pt. Distance = 6.5 to 7.6 mm MIN SCR = *7 min Stress = 23.5 MPa, Biaxial Pt. Distance = 7.6 mm *56 PSI – 22 deg C – 0.2% caustic

CASE STUDY 1 MAX SCR = 91 min MIN SCR = 14 min Stress = 16.0 MPa, Asymmetry = 6 MIN SCR = 14 min Stress = 23 MPa, Asymmetry = 18 *56 PSI – 22 deg C – 0.2% caustic

STATISTICALLY SIGNIFICANT > 99.9% CONFIDENCE LEVEL CASE STUDY 1 STATISTICALLY SIGNIFICANT > 99.9% CONFIDENCE LEVEL R2 = 70% VARIATION IN SCR ACCOUNTED FOR (minutes to failure) 79 43 20 Measured Predicted 7 1 P-Value < 0.001 R2 = 0.70 Predicted (7) (7) 1 7 20 43 79

CASE STUDY 2 CASE STUDY 2 PROCESS CHANGE VS. STRESS VS. SCR

CASE STUDY 2 Δ injection packing weight = 0.3 gm 7% Δ dist. to biaxial pt. 49.3 gm. 11 min Δ SCR 49.0 gm.

CASE STUDY 2 Δ lamp zone 6 = 10% 24% Δ stress 9 min Δ SCR

CASE STUDY 2 Δ pre-blow cam = 8 deg. 14% Δ stress 5 min Δ SCR

Ability to Detect Process Change with Control Charts CASE STUDY 3 DETECTING PROCESS CHANGE WITH BASE THICKNESS VS. STRESS MEASUREMENT

Thickness – Injection Point, Transition Point PROCESS CONTROL VIA BASE THICKNESS Thickness – Injection Point, Transition Point GATE THICKNESS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Subgroup Number FOOT THICKNESS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Subgroup Number Process Change Detected

DISTANCE TO BIAXIAL POINTS PROCESS CONTROL VIA STRESS MEASUREMENT AVERAGE STRESS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Subgroup Number DISTANCE TO BIAXIAL POINTS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Subgroup Number Process Change Detected

Stress & Dist. To Biaxial Pts. PROCESS CONTROL VIA STRESS MEASUREMENT Stress & Dist. To Biaxial Pts. AVERAGE STRESS NO Post Mold Spray Earlier PB Hotter Base Reduced stretch-rod gap Original Process DISTANCE TO BIAXIAL POINTS

CONCLUSIONS CONCLUSIONS

CONCLUSIONS Stress Crack Failure Risk Still with Us After 40 Years Historical Gaps in Capability to Control Processes for SCR New Quantitative Stress Measurement Technology: Closes Gaps in Assessing PET Container SCR Provides Valuable Input for Process Optimization Excellent Detection of Consequential Process Change

CONCLUSIONS THANK YOU!